During the drilling of boreholes, such as occasioned in seeking oil and gas production, the drilling rigs must have made available a nearby large storage pond, called a mud pit, so that drilling mud can be mixed with various different chemical additives in order to carry out a proper drilling operation. Brine is often used in tremendous quantities in drilling operations, and the handling of thousands of gallons of salt water is costly and must be carefully contained in order to avoid waste and contamination of the immediate area. It is especially important that the brine be contained within a reliable storage pond or tank in order to prevent damage to the underlying aquifier as may occur by the salts and chemicals escaping through the tank bottom and soaking into the fresh water zone. Moreover, vegetation, livestock, and wild animal life must be protected from runoff and spillage of the various chemicals employed in drilling a borehole.
Heretofore, the important of lining earthen tanks have been ignored, or else the tanks have been inadequately lined by cementing together the edges of several polyethylene sheets. This is difficult to properly carry out in the field because the wind blows the lightweight polyethylene about, making it difficult to effect a proper bond at the seams; and furthermore, dirt and debris is blown onto the glue, causing the seam to subsequently part. The polyethylene liner is easily damaged by rocks and other sharp objects. Moreover, air entrapped under the plastic liner tends to float the enter liner to the surface; and therefore, it is not unusual for the workmen to attempt to overcome this drawback by throwing weights, rocks, and other debris into the tank. Of course, this action contributes to the danger of injuring the liner as well as contaminating the contents of the tank.
Therefore, it is desirable to have a tank liner in the form of a unitary membrane which is impervious to drilling mud, chemical additives, and salt water. It would be desirable that the membrane be efficiently fabricated insitu to form a monocoque liner which overcomes the above drawbacks and which is not easily damaged.